1. Field of the Disclosure
The present application relates to light-emitting diode drive circuit and method.
2. Description of the Related Art
Recently, a variety of light-emitting technologies are being researched in display device field, in order to meet customer's demands for eco-friendly and low power products.
The currently used display devices include plasma display devices, liquid crystal display (LCD) devices, light-emitting diode (LED) display devices and so on. Among the display devices, the LED display devices are self-illuminating display devices each configured to drive a voltage between both electrodes. The LED display devices are spotlighted as next generation display devices because of having features such as stability, less heat generation and low power consumption. Such LED display devices have been used for illumination devices and backlight units of the LCD devices.
An LED drive circuit of the related art includes an LED array configured to include a plurality of parallel connected LED strings, constant current drivers disposed at the respective LED strings, and a system controller configured to control the operation of the LED array. Each of the LED strings includes a plurality of serially connected LEDs.
In general, a fixed reference voltage is applied to the system controller. The system controller compares the least drive voltage among drive voltages measured in the LED strings with the fixed reference voltage and controls the LED array based on the compared resultant.
If the least drive voltage among the drive voltage measured in the LED array is lower than the fixed reference voltage, the system controller raises the drive voltage. On the contrary, when the least drive voltage among the drive voltages measured in the LED array is higher than the fixed reference voltage, the system controller lowers the drive voltage which is used to drive the LED array.
However, the plurality of LED strings within the LED array is connected parallel to one another. Also, signals on each of the LED strings are often distorted due to external environment. The related art LED drive circuit controlling the drive voltage based on the fixed reference must have vulnerabilities to the external environment.
In other words, external noise components can be input to each of the LED strings. As such, the measured drive voltages must include the noise components. Nevertheless, the drive voltage is adjusted through the comparison of the measured drive voltage and the fixed reference voltage without considering the noise components. Due to this, the related art LED drive circuit must be easily affected by the external environment.